The proposed study will implement and test an innovative and highly significant prevention program by integrating an existing school-based parent program with a youth prevention intervention into a new community-based approach to prevent substance use among acculturating Mexican heritage youth. This research applies the ecodevelopmental approach to strengthen family functioning, reduce youth's acculturative stress, and increase youth drug refusal skills. The intervention will prevent youth substance use as a means of reducing health disparities. The guiding hypothesis is that by synchronizing the two interventions in a community-based setting, the intervention will yield stronger youth and parent desired outcomes and will be more cost-effective. This hypothesis will be tested through a randomized control trial (RCT) in a community-based setting with hard-to-reach, underserved and vulnerable Latino (mostly of Mexican heritage) families. The RCT will compare 1) The aligned Parent-Youth intervention, with 2) The Parent-Only intervention; and 3) Control (treatment as usual). The study will test hypothesized mediators (e.g., family functioning, parenting skills and social support) and moderators (acculturation and acculturative stress) of the effectiveness of the program. The findings will increase knowledge about sustainable and efficacious community-based prevention and about specific approaches to overcome barriers to prevention that are present in the changing social and school environments of the Southwest and the nation.